In a known process of the type in question, the gas to be purified is first removed from the regions producing the impurities. Such regions can be, for example, the cases of printing machines, but other elements that pollute gas or air lie within the scope of the invention. According to the prior art, the gas to be purified is led through piping to an arrangement of several adsorber-filter cartridges, in which the impurities are separated from the gas. The adsorber-filter cartridges are filled with an adsorbing medium suitable for purifying gas, for example with activated carbon. In order periodically to regenerate the adsorber-filter cartridges in a cyclical manner, they are separated from the exhaust-air stream. Subsequently, an expelling medium is introduced that is suitable for purifying or regenerating the adsorber material used in the adsorber-filter cartridges, for example water vapor. The cyclically recurring regeneration process generally occurs in this manner: besides a number of adsorber-filter cartridges assigned to the continuous carrying out of the purification process of the gas and thus running in the adsorber operation, provision is made for at least one additional adsorber-filter cartridge that is just now regenerated. The regeneration process cyclically alternates through the several adsorber-filter cartridges.
Now, it becomes apparent in the prior art that after the conclusion of a regeneration process, the regenerated adsorber-filter cartridge cannot immediately and readily be transferred into the adsorber mode. As a rule, freshly regenerated adsorber-filter cartridges are loaded to a high degree with the expelling medium and have a relatively high temperature. This means that, for instance with the use of water vapor as an expelling medium, upon a sudden introduction of a large mass of cold gas an extreme moistening of the gas occurs in the outlet region of the adsorber-filter cartridge. If such gas or such air were to be led, for example, into the case of a printing machine, a normal operation of the printing machine would be impossible.
For these reasons one proceeds first of all to cool down freshly-regenerated adsorber-filter cartridges and to ensure that the water contained in the adsorber material is removed from the filter cartridge. In this process, water vapor loaded with the residue of the filtered-out chemicals is blown into the atmosphere. Furthermore, on the basis of the described problem (the introduction of moisture from the adsorber-filter cartridges into the printing machine cases), with the application of such adsorber-filter cartridges in the field of printing-machine exhaust air purification one has refrained from driving the exhaust air in a recirculating-air system. This means that greater amounts of fresh air must be supplied to the air stream, which fresh air must be warmed up to a greater or lesser degree depending on the outside temperature. This is associated with a not inconsiderable additional energy consumption in the operation of printing machines.